⚠️ Boxed Warning (All GLP-1 Medications)

Thyroid C-cell tumors have been observed in rodents. GLP-1 medications are contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). It is unknown whether GLP-1 medications cause thyroid C-cell tumors in humans.

Common Side Effects

Gastrointestinal side effects are the most common with all GLP-1 medications. They typically improve over 4-8 weeks as your body adjusts.

🤢 Nausea 15-44%

The most common side effect, especially during dose escalation. Usually mild to moderate and improves over time. More common with higher doses used for weight loss.

🚽 Diarrhea 9-30%

May occur in the first few weeks. Stay hydrated and consider reducing fat intake. Usually resolves on its own.

🤮 Vomiting 6-27%

More common with tirzepatide (Mounjaro/Zepbound). Eating smaller meals and avoiding fatty foods can help.

💨 Constipation 5-24%

Related to slowed gastric emptying. Increase fiber intake, stay hydrated, and consider a stool softener if persistent.

😖 Abdominal Pain 5-20%

Usually mild. Severe or persistent abdominal pain (especially radiating to back) may indicate pancreatitis — seek medical attention.

💉 Injection Site Reactions 3-6%

Redness, swelling, or itching at the injection site. Usually mild and temporary. Rotate injection sites to minimize.

😴 Fatigue 4-11%

May be related to reduced caloric intake. Ensure adequate nutrition despite reduced appetite.

🤕 Headache 4-14%

Usually mild and resolves within the first few weeks of treatment.

Serious Side Effects

These are rare but important to know about. Seek medical attention if you experience any of these:

🏥 Pancreatitis

Warning signs: Severe abdominal pain that doesn't go away, pain radiating to your back, nausea/vomiting that won't stop. Action: Stop the medication and seek immediate medical care. Risk is increased in patients with a history of pancreatitis.

🫀 Gallbladder Disease

Warning signs: Upper right abdominal pain, pain after eating fatty foods, nausea, fever. Why it happens: Rapid weight loss increases gallstone formation risk. More common with higher weight loss. May require gallbladder removal.

🧪 Acute Kidney Injury

Warning signs: Decreased urination, swelling in legs/ankles, fatigue, confusion. Why it happens: Usually related to dehydration from persistent vomiting or diarrhea. Stay well hydrated, especially during GI symptoms.

👁️ Diabetic Retinopathy Complications

Who's at risk: Patients with existing diabetic retinopathy. Rapid improvement in blood sugar can sometimes worsen retinopathy temporarily. Regular eye exams recommended.

📉 Hypoglycemia (Low Blood Sugar)

When: Primarily when combined with insulin or sulfonylureas. Warning signs: Shakiness, sweating, confusion, rapid heartbeat, dizziness. Action: Your doctor may reduce your insulin or sulfonylurea dose when starting a GLP-1.

⚠️ Allergic Reactions

Warning signs: Rash, itching, difficulty breathing, swelling of face/lips/tongue. Action: Seek immediate medical attention. Do not take further doses.

How to Minimize Side Effects

Start Low, Go Slow

Always follow the titration schedule (usually 4 weeks at each dose)
If side effects are severe, your doctor may slow down the dose escalation
Don't skip doses — inconsistent use can worsen side effects

Eating Strategies

Eat smaller, more frequent meals instead of large meals
Avoid fatty, greasy, and fried foods — they worsen nausea
Eat slowly and stop when you feel comfortably full
Avoid lying down immediately after eating
Bland foods (crackers, toast, rice) may help during nausea

Stay Hydrated

Drink plenty of water throughout the day
Replace electrolytes if you have diarrhea or vomiting
Dehydration can lead to kidney problems

Timing Tips

Take your injection at the same time each week
Some patients find fewer side effects when injecting in the evening or before bed
For oral semaglutide (Rybelsus): take on empty stomach, 30+ minutes before food/drink

💡 When to Call Your Doctor

Contact your healthcare provider if: side effects don't improve after 4-6 weeks, you can't keep food or fluids down, you have severe abdominal pain, or you're losing weight too rapidly (more than 2 lbs per week consistently).

Special Populations

Pregnancy & Breastfeeding

GLP-1 medications should be stopped at least 2 months before planned pregnancy. Animal studies show potential fetal harm. Not recommended during breastfeeding due to unknown effects.

Elderly Patients (≥65 years)

No dose adjustment needed, but monitor more closely for dehydration and side effects. Start with lowest dose and titrate slowly.

Kidney Disease

No dose adjustment for mild-moderate kidney impairment. Use caution in severe kidney disease. Monitor closely for GI side effects that could cause dehydration.

History of Pancreatitis

GLP-1 medications are not strictly contraindicated but should be used with caution. Discuss risks and benefits with your doctor. Monitor for symptoms closely.

GLP-1 Side Effects & Safety